president obama planning to visit boston today to pay tribute to victims of the marathon bombings on monday. the death toll from monday's explosion remains at three with more than 170 injured including some who had to have their limbs amputated. surveillance video appears to be the focus of the investigation now and as susan mcginnis reports, images show at least one suspicious man just before the explosions. >>> reporter: the scene of the second bomb that went off during monday's boston marathon may give us our first look at the suspected bomber. sources tell cbs news that security cameras at a lord & taylor store captured a man leaving a bag in the area just before the blast. the suspect is described as a young white man seen carrying a backpack and talking on a cell phone. sources say he was wearing a black jacket, a gray hoodie and white baseball cap turned backwards on his head. just after the first bomb went off, the suspect left the scene. moments later, the second bomb detonated. investigators are also looking at cell phone records hoping to match one of the calls to the man